GB2109594A - Method and apparatus for guidance and control of a vehicle - Google Patents

Abstract

Method and apparatus for guiding a vehicle, the apparatus including means for generating a beam (15) which is detectable by an object to be guided, means (11, 12) for causing the beam to scan along a path (L1, L2) at least a part of which (L2) is curved. In a preferred embodiment the scanning means includes a rotatable reflector (12) powered by a motor (13) through to a shaft (14). In order to provide the curved path (L2), the reflector, which is plane, is rotatable about an axis which is at an angle to the plane thereof. <IMAGE>

Description

SPECIFICATION Method and apparatus for guidance and control of a vehicle This invention relates to the guidance and control of a vehicle, such as an unattended carrier car.

It has been proposed to use, particularly in factories, so-called "carrier cars" that are automatically steered, to transfer products. Such carrier cars follow a specified route by detecting a metallic tape previously put on the ground along the route to be followed, or by being guided by radio signals.

It has also been proposed to define the route to be followed by causing a light beam to scan along the path. In this arrangement the vehicle is provided with means to sense the scanning light beam.

Embodiments of the present invention are directed to the provision of a route or path especially a curved route or path on which a ground-moving object travels, the object being guided, by means of a light-beam irradiating onto a reflector which is turnable or rotatable. A number of poles, erected in the vicinity of the route on which the ground-moving object travels are each provided with a light-beam generating unit, the generated light beam, being reflected by a mirror turnably or rotatably mounted.

Such construction facilitates provision of a curved route, which has heretofore been difficult to produce, along which the ground-moving object can smoothly travel.

An advantage of the invention is that a lightbeam scanning system is provided which can produce a curved route or path.

Another advantage of the invention is that a light-beam scanning system is provided which can produce the curve route or path economically by use of a single light-beam irradiation apparatus and a turnable reflecting means.

Still another advantage of the invention is that a light-beam scanning system is provided which can produce a plurality of paths by use of a single light-beam irradiation apparatus.

A further advantage of the invention is that a light-beam scanning system is provided which can change the route by use of a single lightbeam irradiation apparatus corresponding to the position of each station.

Embodiments of the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a plan view of a guidance system in which the invention may be employed.

Figure 2 is a view taken in the direction of the arrow A of figure 1.

Figure 3 is a view taken in the direction of the arrow B of figure 2.

Figure 4 is a block diagram of the control circuit for the carrier car shown in figures 1 to 3.

Figure 5 is a view of an embodiment of a lightbeam scanning apparatus according to the invention.

Figure 6 is a view of another embodiment of the invention.

Figure 7 is a schematic illustration showing a route or path on which a ground-moving object travels, which is generated by the figure 2 embodiment.

Figure 8 is a view of another embodiment of the invention.

Figure 9 is a schematic diagram of a laser beam scanning apparatus used in the figure 8 embodiment.

Figure 10 is a view of a route or path change effected by use of the laser beam scanning apparatus of figure 9.

Figure 11 is a schematic diagram of an embodiment of the invention.

Figure 12 is a view of another embodiment of a laser beam scanning system of the invention, and Figure 13 is a block diagram of a speed control circuit which may be used with the invention, particularly the embodiment of the figure 12.

The basic components of the guidance system are shown in figures 1 to 3. A ground moving object 101 is shown on a path 102, path 102 being defined by a scanning laser beam LB projected from guidance apparatus 103 positioned above the path 102. The guidance apparatus 103 includes a laser beam generator and a scanning means, which causes the laser beam LB to scan along the path 2 (see below).

A control and sensing device 104 is provided on the ground moving object 101, that senses beam LB and provides control signals to the steering mechanism of the object 101,so that it follows the path defined by the beam LB.

A block diagram of the circuitry of the control and sensing device 104 is shown in figure 4. The device 104 has two sensors, 141, 142 connected to respective amplifiers 151,152 which are both connected to a comparison circuit 106, the output of which is fed to the control circuit, for the steering apparatus, 111.

The sensor 141 is mounted on the righthand side of the vehicle 101 as shown in plan in figure 1, the sensor 142 is positioned on the left-hand side of the vehicle 101. Both sensors are positioned so as to be able to detect the laser beam LB when it is scanning the path 102.

In use, the laser beam LB scans along the path 102 thus providing a guiding line for the ground moving object 101. If the ground moving object 101 is following the path exactly, the sensors 141, 142 are symmetrical relative to the path of the laser beam LB, so that the sensors provide equal signals to the comparison circuit 106. In this situation, the comparator circuit 106 does not output any signal to the steering control circuit 111. If the ground movable object veers to the right of the guiding line, only the sensor 142 receives the laser beam LB. The output signal from the sensor 142 supplied via its corresponding amplifier 152, to the comparison circuit 106 is therefore greater than that supplied from the sensor 141 and corresponding amplifier 1 51 to the comparison circuit 106.The comparison circuit 106 then provides an output signal to the steering control circuit 111, which adjusts the steering so as to bring the ground movable object 101 back into line with the beam LB. When the ground movable object 101 veers to the left, the reverse situation to that described above happens, and the comparison circuit 106 provides an opposite sense output signal to the steering control circuit 111 , so that the ground movable object 101 is steered back towards the right and thus into line with the laser beam LB.

The scanning apparatus 103 will now be described.

With reference to figure 5, reference numeral 10 designates a reflector body. A main path scanning reflector 11 is fixed to the reflector body 10 in parallel to a shaft 14. A bypass reflector 12, having a predetermined tilt angle 0, with respect to the rotary shaft 14, is also fixed to the reflector body 10, the reflector body 10 being rotatably driven through the shaft 14 at a constant speed by a motor 13.

Reference numeral 1 5 designates a wellknown laser beam generating apparatus, the apparatus 1 5 projecting a laser beam LB having high directivity at the rotatably driven reflector 10.

The laser beam LB is thus reflected by the rotating main line scanning reflector 11 and traces a main route or path L, on a floor surface 16 as shown in figure 1. Since the axis of the rotary shaft 14 of reflector body 10 is set perpendicularly with respect to the laser beam LB, the laser beam LB reflected by the main line scanning reflector 11 traces the route or path L, on the floor surface 1 6 as a straight line.

The laser beam LB is also reflected by the bypass scanning reflector 1 2 as the reflector body 10 rotates. Since the bypass scanning reflector 12 is mounted at the predetermined tilt angle 0, with respect to the rotary shaft 14, the laser beam LB reflected by the rotating bypass scanning reflector 1 2 traces a curved bypass route L2 on the floor surface 1 6. The degree of variance between the bypass path L2 and the main path L depends upon the tilt angle 0, of the bypass scanning reflector 12.

In this way, a single laser-beam generating apparatus can be used to obtain a plurality of different bypass paths L2 in addition to the main path L,,depending on the tilt angle 6i, without requiring excessive expenditure.

In order to provide either the main path L, or the bypass path L2 at any one time, the laser beam LB may be pulsed so that the beam LB is only reflected by one reflector (e.g. 11) or the other reflector (e.g. 12) during one revolution of the reflector body 1 0.

Another embodiment of the invention will now be described.

Referring to figure 6, reference numeral 1 7 designates a scanning reflector turnable or rotatable by a motor 1 3. The scanning reflector 1 7 is fixed to a rotary shaft 14 so that the normal to the plane of reflector 1 7 is inclined at a predetermined tilt angle 62 with respect to the axis of the rotary shaft 14.Reference numeral 1 5 designates a laser beam generating apparatus placed horizontally with respect to the floor surface 16, the laser beam LB being projected from the laser-beam generating apparatus 1 5 and being reflected along the extension of the axis of rotation of scanning reflector 1 7 by a stationary reflector 1 9 fixedly disposed so that the laser beam LB reflected by the stationary reflector 1 9 is coincident with the axis of the rotary shaft 14 of scanning reflector 1 7, so that the laser beam LB is reflected by the rotating scanning reflector 1 7 to describe a circular or arcuate path L on the floor surface 16, during the rotation of scanning reflector 1 7. The radius R of path L, when a height from the floor surface 1 6 to the reflector 17 is represented by H, is given by R=H.tan202 (where 62 is the tilt angle between the normal of reflector 1 7 and the axis of rotary shaft 14).

Therefore, the height H of reflector 17 from the floor surface 1 6 or the tilt angle 62 of reflector 1 7 can be altered to give a radius R of the line L of a desired value.

Referring to figure 6, the route of a groundmoving object is shown, which is traced using the figure 7 embodiment.

In figure 7-(a), lines L, and L2 are drawn by use of the present invention, in which the scanning reflector 17 turns through 1 80a, while, lines L3 and L4 are generated by straight-line laser beam scanning.

In figure 7-(b), lines L5, L6 and L7 each at an optional angle are shown, which are obtainable by combination of apparatus used in the invention for generating line L7 and straight line scanning apparatus for generating lines L5 and Le.

As seen from the above, the scanning method of the invention can obtain a desired curved route by use of the single laser-beam generating apparatus, thereby desirably changing the travelling direction of the ground-moving object.

Another embodiment of the invention will now be described with reference to figure 8, in which reference numeral 1 5 designates a laser-beam generating apparatus, 20 designates a reflector, 13 designates a motor for rotating or turning the reflector 20, 1 6 designates the floor surface, and LB designates a laser beam.

In figure 8-(a), the reflector 20 is slanted at an angle 0 with respect to the axis of the rotary shaft, and the axis thereof is perpendicular to the laser beam LB, whereby the laser beam LB, scanning as the reflector 20 rotates, traces a straight line L, on the floor surface 16.

In figure 8-(b), the reflector 20 is slanted at the predetermined angle 63 with respect to the axis of the rotary shaft of reflector 20, resulting in the laser beam LB scanning as the reflector 20 rotates so as to draw a curve L2 on the floor surface 16.

The curvature of the curve L2 depends upon the tilt angle 63 so that a desired route L2 is obtainable by changing the angle 63, thus enabling the ground-moving object to change its route.

Referring to figure 9, the laser-beam scanning apparatus used in the figure 8 embodiment is shown, in which reflectors 21 and 22 are mounted, at one end thereof through hinges 25 onto a rotary shaft 24 rotatably driven by a motor 23. Tension springs 26 are attached to the other respective ends of the reflectors 21, 22. A drive rod 28 driven by the reflector driving motor 27 abuts against the inner surfaces of reflectors 21 and 22 respectively, the drive rod 28 being movable vertically to set the reflectors 21 and 22 at a desired tilt angle 63 with respect to the axis of the shaft 24. The motor 27 is prevented from rotating itself, by means of a L-shaped support rod 29 vertically movable relative to the drive rod 28 in a bore 28A.In addition, in figure 9, a reference numeral 27A designates a bearing for the rotary shaft 24, 27B designates a threaded shaft rotatably coupling with the reflector driving motor 27 through a coupling 27E, 27C designates an internally thread joint vertically movable in mesh with the threaded shaft 27B as it rotates, and 27D designates a retainer for retaining one end of each tension spring 26.

The laser beam scanning apparatus constructed, as shown in figure 9, is provided at a predetermined distance away from the laserbeam generating apparatus 1 5. The reflectors 21 and 22 are rotatably driven by the motor 27 to allow the incident laser beam to scan. Figure 10 shows the path drawn by the scanning laser beam through the reflectors 21 and 22, a station 30 being positioned at the point A on the route L1.

In this case, assuming that the station 30 moves to the point B away from the point A by a distance X, the reflectors gradually change their tilt angle 03. The laser beam then describes a path through the point B, thereby obtaining a route L2 as shown.

As a result, the ground-moving object 31 travelling along the route L, changes its direction as the route L, changes into L2, thereby arriving at the station 30 now positioned at the point B.

Hence, if other moving objects or obstacles are on the route L1, the moving object 31 can change its travelling path by use of the route L2.

As seen from the above, the invention can be used to change the route of a ground-moving object corresponding to the position of a station, this being practically convenient. Also, the station, from the above reason, need not be provided at a fixed point, which is very economical.

A description will now be given of another embodiment of the present invention.

In figure 11, a translucent apparatus, for example, a half-transmission prism 32, is provided at the predetermined distance from a laser-beam generating apparatus 1 5 so that the laser beam LB generated by the laser-beam generating apparatus 1 5 is divided into a laser beam LB1 in part transmitted through the prism 32, and a laser beam LB2 reflected in part from the slanting surface of prism 32, whereby a spectrum at a desired angle is observed, the laser beam LB2 then being reflected by a total reflection prism 33.

Reference numeral 34 designates a reflector provided at a predetermined distance from the laser-beam generating apparatus 1 5 across the half-transmission prism 32. The reflector 34 is rotatable to a desired angle around the axis perpendicular to the travelling direction of laser beam Lob1, thereby reflecting the laser beam LB, and allowing it to scan sequentially on the floor surface on which the object travels. The scanning by the laser beam LB1 is the same straight line technique as that shown in figure 8a.

A reflector 35 the same in construction as the reflector 34 is provided in the path of the laser beam LB2 reflected by the total reflection prism 33 so that the laser beam LB2 traces a path different from that of laser beam LB1 reflected by the reflector 34.

Where vibrations are caused by travel of the ground-moving object or other factors, the prisms and reflectors can vibrate to make it impossible for the laser beam to be reflected with accuracy.

In order to eliminate this and increase flexibility regarding the positions where the reflectors and prisms are to be fixed, optical fibers can be used to perform guidance of the laser beam within the laser-beam generating apparatus. Where a half prism is provided at a predetermined distance from the laser-beam generating apparatus so that it transmits in part and reflects in part the generated laser beam LB therefrom and two reflectors (corresponding to the reflectors 34 and 35 in figure 6) at the desired positions are rotated or turned, the optical fibers are disposed between the laser beam generator and half prism and the half prism and each reflector, the laser beam being guided through the optical fibers.

The embodiment described above can generate two laser beams by a single laser vibrator. Hence, the number of laser beam generators required to provide scanslon for a path can be decreased, thereby making it possible to reduce the number of locations of laser-beam generating apparatus and to prevent a malfunction caused by fluctuation of brightness of one laser vibrator.

Referring to figures 12-(A) and -(B), still another embodiment of the invention will be described, in which a reflector 36 is provided with a rotary shaft 37 positioned at a distance d from the laser beam LB (where if a width of reflector is represented by I, l/2 > d), the rotary shaft 37 being perpendicular to the laser beam LB and parallel to the ground surface.Assuming that the reflector 36 rotates clockwise in the direction of the arrow B in the drawing, the laser beam reflected by the reflector 36 scans the ground surface between the points B" and C" while the reflector 36 is moving within a range between the arrows B and C as shown, but passes the reflector 36 and continues radiating in the same direction when the reflector 36 comes out of the above range, whereby consequently the laser beam will scan intermittently the ground surface as shown in figure 1 2-(B).

As shown in figure 12-(B), the laser beam, scans in pulses A1, A2, A3.... etc. The speed of revolution of the reflector is given to a control circuit of a motor, for rotating the reflector 36 under a command from, for example, a separate central processing unit CPU 1 so that the reflector 36 is precisely controlled and the pulse-like scans A1, A2 and A3 are generated at a given frequency, the frequency being interpreted by the groundmoving object as a speed command.

For example, when the pulse number is 100 per unit time, the speed command of 1 OCM/S is given, and when 300, that of 30CM/S is given.

The ground-moving object, however, usually travels on the route at a set speed of V, so that the pulse number received by a detector in the ground-moving object needs to be related to the actual object speed. A block diagram of a speed command detecting circuit for the ground-moving object is shown in figure 13.

The output from the laser beam detector is counted by a counter, the count number N and the actual speed V of the ground-moving object being given to a central processing unit CPU2, the CPU2 computing the speed command from the CPU1 on a basis of the aforesaid information, and the output from the CPU2 adjusting the speed V of ground-moving object. In a case of considerably increasing the number of rotations of the reflector, the ground-moving object may be assumed to be a stop nearly with respect to the laser beam scanning so that the aforesaid speed detector may be omitted.

In this technique, there are shown in figure 12 (B) regions 8,, B2, B3... where the laser beam has passed the reflector 36. Another separate reflector (not shown) different in rotary phase from the reflector 36 may also be provided further ahead of the reflector 36, to reflect the laser beam LB. In this case, the laser beam can scan over a larger area and here be more effective.

Claims (29)

Claims

1. A method of guiding a vehicle comprising causing a beam to scan along the path along which the vehicle is to move, at least a portion of said path being curved, detecting said beam at said vehicle, and guiding the vehicle in accordance with the detected beam.

2. A method according to claim 1, in which the beam is a light beam.

3. A method according to claim 2, in which the beam is generated by a laser.

4. A method according to any preceding claim, in which the scanning is achieved by reflecting the beam from a rotating reflector.

5. A method according to claim 4, wherein said reflector is plane and the axis of rotation thereof is at an angle to the plane of the reflector to cause said beam to define a curved path.

6. Guidance apparatus comprising means for generating a beam which iS detectable by an object to be guided and means for causing said beam to scan along a path at least part of which is curved.

7. Apparatus according to claim 6, wherein said beam is a light beam.

8. Apparatus according to claim 7, wherein said generator is a laser.

9. Apparatus according to any of claims 6 to 8, wherein said scanning means comprises a rotatable reflector.

1 0. Apparatus according to claim 9, wherein said reflector is plane and is rotatable about an axis which is at an angle to the plane thereof to cause said scanning along a curve.

11. Apparatus according to claim 10, wherein said reflector is adjustably mounted to permit adjustment of said angle.

1 2. A method of controlling the speed of an object which comprises repeatedly scanning a beam along the path along which the object is to move and controlling the speed of the object in accordance with the frequency of said scanning.

13. A method according to claim 12, in which the beam is a light beam.

14. A method according to claim 13, in which the beam is generated by a laser.

1 5. A method according to any of claims 12 to 14 in which said scanning is achieved by reflecting the beam from a rotating reflector.

16. A method according to claim 1 5 in which said frequency is proportional to the rotational speed of said reflector.

1 7. Apparatus for controlling the speed of a vehicle comprising a sensing device responsive to the frequency of incident radiation.

1 8. Guidance apparatus comprising means for generating a beam, means for causing the beam to be split into a plurality of secondary beams, each secondary beam being detectable by an object to be guided and means for causing each secondary beam to scan along a portion of a path.

1 9. Apparatus as claimed in claim 1 8 wherein said splitting means comprises a prism.

20. Apparatus as claimed in claim 18 or claim 1 9 wherein, optical connections between said generating means and said splitting means and said splitting means and said scanning means are formed using optical fibers.

21. A light-beam scanning method for guiding and controlling a ground-moving object which receives and detects a light beam and is guided therewith to travel on the ground, said scanning method characterized in that a rotatable reflector body is placed away at the predetermined distance from a single light-beam generating apparatus so that the light beam from said lightbeam generating apparatus is irradiated onto a plurality of reflectors fixedly mounted to a rotary shaft of said reflector body at the predetermined angles with respect to the axis of said rotary shaft, thereby performing a plurality of scans by said light beam.

22. A light-beam scanning method for guiding and controlling a ground-moving object which receives and detects a light-beam and is guided therewith to travel on the floor surface, said scanning method characterized in that a rotatable or turnable scanning reflector is placed away at a predetermined distance from a single light-beam generating apparatus, said scanning reflector being fixedly mounted onto a rotary shaft so that the normal to said reflector is slanted at a predetermined angle O with respect to the axis of said rotary or turning shaft, said rotatable or turnable scanning reflector being irradiated by a light beam at the predetermined angle from said light-beam generating apparatus, so that the light-beam scans on the floor surface to draw a curved route.

23. A light-beam scanning method for guiding and controlling a ground-moving object which receives and detects a light beam and is guided therewith to travel on the floor surface, said scanning method characterized in that a rotatable or turnable reflector is placed away at the predetermined distance from a light-beam generating apparatus, so that said reflector makes variable a tilt angle with respect to the axis of a rotary shaft of said reflector, thereby allowing the light beam incident on said reflector to be variable of the scanning direction of said light beam.

24. A light-beam scanning apparatus for controlling a ground-moving object which receives and detects a light beam and is guided therewith to travel on the floor surface, said apparatus characterized in that said light-beam scanning apparatus has one or more reflectors rotatable and turnable by being driven by a motor, and at least one of said reflectors is variable at a tilt angle with respect to the axis of a rotary shaft of said reflector on a basis of being driven by a motor separately provided.

25. Guidance apparatus as hereinbefore described with reference to any of figures 1 to 5 of the accompanying drawings.

26. Guidance apparatus as hereinbefore described with reference to either of figures 6 or 7 of the accompanying drawings.

27. Guidance apparatus as hereinbefore described with reference to any of figures 8 to 10 of the accompanying drawings.

28. Guidance apparatus as hereinbefore described with reference to figure 11 of the accompanying drawings.

29. Guidance apparatus as hereinbefore described with reference to either of figures 12 or 13 of the accompanying drawings.